Device for breaking down coal and the like



Oct. l, 1963 J. c. HEssoN ETAL 3,105,437

DEVICE Foa BREAKING nowN com. AND THE LIKE Filed March l2, 1962 2 Sheets-Sheet l INVENTORS INN bw 0% n.

wm. am n Q Oct. l, 1963 Filed March l2, 1962 J. c. HEssoN ETAL 3,105,437

DEVICE FOR BREAKING DOWN COAL AND THE LIKE 2 Sheets-Sheet 2 United States Patent Oiiice 3,105,437 Patented Oct. 1, 1963 3,105,437 DEVICE FGR BREAKING DOWN COAL AND THE LIKE James C. Hessen, Riverdale, and Ralph S. Frost, Olympia Fields, Ill., assignors to Marmon-Herrington Company,

Inc., Oak Hill, W. Va., a corporation of Indiana Filed Mar. 12, 1962, Ser. No. 178,857 11 Claims. (Cl. 102-25) Our invention relates to compressed gas devices for breaking `down material, such as coal, slag and the like.

One form of such devices employs air compresse-d to a pressure of the order of 10,000 lbs. per square inch in a metallic cartridge. Air at this pressure can be obtained from a suitable compressor and supplied to the cartridge through a suitable conduit all as well known to those skilled in the art. Provision is made for quickly releasing the charge of compressed air through lateral discharge ports in the cartridge when it is placed in a drilled hole in a coal face. For this purpose `the discharge ports are closed off from the charge containing chamber by an annular discharge valve which is held closed against an annular seat by a force acting thereon in a valve closing direction that is provided by compressed air in a control chamber located endwise of the charge containing charnber. The vdischarge valve is thus held closed until the force exerted by `the charge of compressed gas on the discharge valve in an opening direction exceeds the force acting to hold it closed whereupon the valve is moved quickly to open position to permit the charge of compressed gas to flow through the discharge ports into the drilled hole to break down the coal or other material in which the cartridge may be located. The force exerted on the discharge valve by the compressed gas in the control chamber continues to bias it to the closed position and it is reclosed as soon as this force exceeds the force exerted threon by the charge of compressed gas in the chamber which is reduced as a result of its discharge through the discharge ports. This takes place before the material breaking charge has been completely dissipated and the discharge valve recloses leaving a substantial portion of the material breaking charge `trapped in its chamber and in the supply conduit from the air oompressor. The trapped charge, while at a pressure substantially less than the maximum pressure, is such that it may be dangerous to manipulate the cartridge manually since the discharge valve may be opened accidentally. In addition, it is desirable to discharge substantially completely the material breaking charge through the discharge ports in order to obtain full advantage of the entire charge for material breaking purposes.

Accordingly, an important object of our invention is to provide for holding the discharge valve of a material breaking cartridge in the open position in a new and improved manner until the material breaking charge has been substantially completely discharged through lateral discharge ports otherwise closed by the discharge valve.

Another object of our invention is to provide an intermediate chamber between the charge containing charnber and the control chamber in communication with the `former through restricted orifice means to create in the intermediate chamber a force acting `on the discharge valve in la direction to hold it open against the force of the compressed gas in the control chamber biasing it closed to the end that the discharge valve will be held in the open position by a portion of the charge trapped in the intermediate chamber for a time suicient to permit the material breaking charge to be substantially completely discharged through the discharge ports.

Still another object of our invention is to derive the compressed gas in the control chamber from the charge in the charge containing chamber as it is being built up therein and to hold such charge in the control chamber by suitable valve means which permit `the same to be replenished when required.

A further object of our invention is to provide for limiting the pressure built up in the control chamber by the provision `of suitable relief valve means therefor.

Still another object of our invention is to provide the restricted orifice means between the charge containing chamber and the intermediate chamber either in the form of a restricted passageway through a baille separating the two chambers or through a restricted annular space between the baille and the interior of the annular discharge valve telescoped with the baille.

An additional object of our invention is to provide for adjusting the volume of the control chamber by adjustably mounting a relatively stationary piston teleseoped with the annular valve, the piston providing at one end one wall of the intermediate chamber land at the other end one wall of the control chamber.

In the drawings:

FIG. 1 is a longitudinal sectional view of a material breaking cartridge in which the present invention is emb-odied.

FIG. 2 is a view, at an enlarged scale, of the discharge end of the cartridge as shown in FIG. 1 and because of the enlarged scale reference characters are applied here that are not applied in FIG. l.

FIG. 3 is a view, similar to FIG. 2, but showing a modification, the same reference characters being employed in FIG. 3 that are employed in FIG. 2 where the parts are identical.

FIG. 4 is a view, similar to FIGS. 2 and 3, and shows a further modification of the invention, the same parts as employed in FIGS. 2 and 3 bearing the same reference characters.

Referring `now particularly to FIG. 1 of the drawings, it will be observed that the reference character 10 designates, generally, a material breaking cartridge embodying one form of our invention. The material breaking cartridge 10 includes a cylinder metallic cartridge tube that is threaded at one end to a metallic tube top 12. Filling passageway 13 extends through the tube top 12 and is connected to an air supply tube 14 which, it will be understood, is connected to a suitable source of compressed gas such as compressed air. A clamp nut 15 serves to hold the air supply tube 14 in sealed contact engagement with the tube top 12 and in alignment with the lilling passageway 13. An O ring seal 16 is interposed between the cartridge tube 11 and the tube top 12 to provide a sealed connection therebetween. Another O ring seal 17 `is located at the other end of the cartridge tube 11 and between it and a cylindrical metallic extension adapter 18 with which it has a threaded connection.

Threaded onto the other end of the extension adapter 18 is a cylindrical tubular housing 19 that is provided with lateral discharge ports 20 which are inclined away from the outer end of the cylindrical tubular housing 19 in conventional `manner and through which the charge of compressed air in the charge containing chamber 2l within the cylindrical cartridge tube 11 is discharged for breaking down coal and the like. It will be understood that the charge containing chamber 21 includes a portion of the tube top 12 and the interior of the cylindrical extension adapter 18. It is within this charge containing chamber 21 that the gas is built up to a pressure of the order of 10,000 lbs. per square inch for release through the lateral discharge ports 20 in a manner to be described.

As shown in FIGS. 1 and 2 of the drawings the lateral dischange ports normally are closed by an annular discharge valve 24 that is slidably mounted within the cylindrical interior of the tubular housing 19. At its left end, as shown in these figures of the drawings, the annular discharge valve 24 has an annular contact surface 25 which is held in sealed engagement with an annular valve seat 26 that is located on the right end of the extension adapter 18. The annular valve seat 26 preferably is as nearly a knife edge as possible in order to provide the desired sealed engagement with the juxtaposed annular contact surface 25. The diameter of the annular valve seat 26 is indicated at 27.

The left end of the annular discharge valve 24 is closed off `for the major portion of the area thereof by a bottom wall 28 which has a central aperture 29. The discharge valve 24 with the bottom wall 2S provides a substantially cup shaped configuration and defines a chamber therein the diameter of which is indicated at 31. The diameter of the central aperture 29 is such that, when the chamber 2l is filled with the charge to be released, the pressure in the chamber 30 is substantially the same as that in the chamber 21 with the result that the same unit pressure is exerted on opposite sides of the bottom wall 28 that are exposed to the pressure of the charge.

With a view to providing a construction which will hold the annular discharge valve 24 in the open position, once it has been moved to this position for a time sufficient to permit the charge in the chamber 21 to be substantially completely discharged, a transverse stationary metallic baille 32 is provided in telescopic relationship within the annular discharge valve 24. An O ring seal 33 along the periphery of the stationary baffle 32 serves to provide a sealed connection to the interior of the annular discharge valve 24 while permitting relative longitudinal movement in the opening and closing directions.

The transverse stationary bathe 32 defines, in part, an intermediate chamber 34 between the charge containing chamber 21 and a control chamber 35 that is located at the right end of the tubular housing 19. As will be pointed out in more detail hereinafter, a charge of compressed gas is supplied to the control chamber 35 and it serves to bias the annular discharge valve 24 to the closed position.

It is desirable to fill the intermediate chamber 34 with a charge of compressed gas as the chambers 21 and 30 are being filled. The reason for this is to exert a force on the annular discharge valve 24 in an opening direction and to maintain this force for a time after the annular discharge valve 24 has moved to the open position long enough for the charge in the chamber 21 to be substantially completely discharged through the discharge ports 20 and also to permit any charge remaining in the air supply tube 14 to be similarly discharged. For this purpose a longitudinal passageway 36 extends through the transverse stationary baffle 32 and into a stem 37 that extends laterally therefrom. The intermediate chamber 34 is filled with a portion of the charge that is supplied to the chambers 21 and 30 through the longitudinal passageway 36 and through restricted orifice means in the form of a radial passageway 38 that extends from the passageway 36 into the intermediate chamber 34. The arrangement is such and the restricted orifice means 38 has such a cross sectional area that, as the charge is supplied to the chambers 21 and 3f). a portion of it fiows into the intermediate chamber 34 to the end that the unit pressure in it increases substantially to the same extent that it increases in the chambers 21 and 30. However, because of the small cross sectional area of the restricted orifice means 38, this portion of the charge of compressed gas in the intermediate charnber 34 cannot quickly escape therefrom `when the annular discharge valve 24 is opened with the result that this remaining portion of the charge is capable of exerting a force in the opening direction of the annular discharge valve 24 to hold it in this position.

In order to take advantage of the force exerted by the portion of the charge in the intermediate chamber 34 an annular discharge valve extension 39 is threaded onto the right end of the annular discharge valve 24 and constitutes an endwise extension thereof. Its internal diameter is indicated at 40 and it is less than the diameter indicated at 27 for the annular valve seat 26 and also is less than the diameter indicated at 31 for the interior off the annular discharge valve 24. At its left end the annular discharge valve extension 39 has an annular surface 41 which faces the transverse stationary baille 32. It is against this annular surface 41 that the portion of the charge in the intermediate charnber 34 reacts to hold the annular discharge valve 24 in the open position after the charge in the chamber 21 is released. The annular discharge valve extension 39 together with the annular discharge valve 24 is slidably mounted within the tubular housing 19 and in the control chamber 35. An O ring seal 42 in the annular discharge valve extension 39 serves to provide a sealed connection between it and the cylindrical inner surface of the tubular housing 19. The gas pressure in the control chamber 35 reacts against the annular right end surface 43 of the annular discharge valve extension 39 in a direction to hold the annular discharge valve 24 closed. With a view to urging the annular discharge valve 24 to the closed position independently of whether or not there is a charge of compressed gas in the control chamber 35, a coil compression spring 44 is provided therein and at one end it reacts against the annular end surface 43. The other end of the spring 44 reacts against an end closure member 4S that is threaded into the right end of the tubular housing 19. An O ring seal 46 provides a sealed connection therebetween to prevent escape of the charge of compressed gas from the control chamber 3S. It will be noted that the diameter of the control chamber 35 is indicated at 47 and that this diameter is the same as the external diameter of the annular discharge valve 24 and of the annular discharge valve extension 39.

The left end of the control chamber 35 is defined, in part, by a relatively stationary piston 49 from which the stem 37 extends. The annular left end surface 50 of the stationary piston 49 defines the right end of the intermediate chamber 34. The intermediate chamber 34 also is defined by the annular inner surface 51 on the right side of the baille 32, the cylindrical inner surface 52 of the annular discharge valve 24 that is located to the right of the battle 32, the annular end surface 41 of the annular discharge valve extension 39, the cylindrical inner surface 53 of the annular discharge valve extension 39 and the cylindrical surface 54 of the stem 37. lt will be understood that, as the discharge valve 24 and the valve extension 39 move to the right in a valve opening direction, the volume of the intermediate chamber 34 is slightly increased and that the volume of the control Chamber 35 is slightly decreased, the extent of increase and decrease, respectively, being in accordance with the extent of movement of the valve extension 39 relative to the intermediate chamber 34 and into the control chamber 35. A sealed connection between the stationary piston 49 and the valve extension 39 is provided by an O ring seal 5S in the former.

The stationary piston 49 is threaded onto the left end of a stern 56 which extends from the left side of the end closure member 45. In order to supply a charge of compressed gas to the control chamber 34 an angular passageway 57 is provided in the stem 56. At one end the passageway 57 communicates with the control chamber 35 and the other end opens into a valve chamber 58 of `relatively large diameter that is centrally located within the stationary piston 49. A coil compression spring 59 in the valve chamber 58 reacts between the left end of the stem 56 and a ball check valve 60 and urges the latter into sealing engagement with an annular valve seat 61 at the right end of an enlarged passage4 way 62 in the piston 49. A restricted passageway 63 places the passageway 62 in communication with the right end of the passageway 36 to the end that compressed gas is supplied from the chambers 21 and 30 as the charge is built up in the chamber 2l. In this manner the charge of compressed `gas in the control chamber 3S is replenished each time that the chamber 21 is charged. The ball check valve 60 is held in closed position by the spring 59 and also by the pressure of the gas in the control chamber 3S to the end that this pressure is maintained. It will be understood that any leakage which takes place from the control chamber 3S is compensated for by a part of the charge supplied to the chambers 21 and 3l) flowing through the restricted passageway 63 and past the ball check valve 60 into the control chamber 35.

It is desirable that the pressure of the compressed gas in the control chamber 35 be limited to a predetermined value. For example, provision can be made for limiting it to a value of the order of 3,000 p.s.i. gauge. For this purpose an annular exhaust passageway 64 is provided in the stem 56 and it opens into the control chamber 3S at one end. At its other end the exhaust passageway 64 has a valve seat 65 that normally is closed by a relief valve member 66 which is slidably mounted in a central opening 67 in the end closure member 45. Longitudinal passageways 68 through the relief valve member 66 place the exhaust passageway 64 in cornmunication with the central opening 67 when the relief valve member 66 is opened. Normally it is held closed by a coil compression spring 69 which reacts between the relief valve member 66 and an adjusting screw 70 that is threaded into a suitable threaded opening located centrally of the right end of the closure member 45. A central exhaust opening 71 extends through the adjusting screw 70 and communicates with the atmosphere through a longitudinal exhaust opening 72 in a cap screw 73. It will be understood that the tension of the spring 69 can be adjusted by shifting the position of the adjusting screw 76 to the end that different pressures can be maintained within the control chamber 3S with certain limits as may be desired.

in operation the control chamber 35 is normally iilled with air at a pressure of the order of 3,000 psi. gauge. It is retained at this pressure by the various ring seals, the ball check valve 60 and the relief valve member 66. The discharge valve 24 is held in sealing engagement against the annular valve seat 26 by the pressure lof the compressed gas in the control chamber 35 and by the force exerted by the spring 44 both acting on the annular end surface 43 of the valve extension 39. The coil compression spring 44 is required only in the event that the air in the control chamber 35 should leak out of it which may take place as a result of a long period of non-use `of the cartridge 10.

As the chamber 2l is lilled with air at high pressure through the air supply tube 14, it flows freely through the aperture 29 into the chamber 3i) and through the passageway 36 and the restricted orifice means 38 into the intermediate chamber 3d. Although the intermediate chamber 34 is charged through the restricted orifice means 38, the arrangement is such that this chamber is filled at such a rate that the pressure per unit area therein is increased to substantially the same extent that the pressure is increased in the chambers 21 and 30. The reason for this is that as compared to the time that is required for opening the annular discharge valve 24, which is of the order of two milliseconds, the time required for filling the chambers 21 and 3!) is relatively great and thus proceeds at a relatively slow speed, requiring a time up to several minutes, depending upon the volume of the chamber 21. When the pressure in the chambers 2l and 3i) exceeds the pressure in the control chamber 35, air slowly ows past the ball check valve 60 and through the restricted passageway 57 into the control chamber 35. The spring loaded relief valve member 66, which is not restricted, prevents the pressure in the control chamber 35 from exceeding the pressure for which the relief valve member 66 is set under the control of the spring 6i). Thus the pressure in the control chamber 35 is maintained substantially constant and this chamber is automatically kept filled to the desired pressure each time that the chambers 21 and 30 are charged.

When the force resulting from the pressure of the compressed gas charge in the chambers 21 and 30 and in the intermediate chamber 34, which pressure acts over the area of the discharge valve 24 which is equal to the diierence between the area of the circle whose diameter is indicated at 27 or the diameter of the valve seat 26 and the area ot the circle whose diameter is indicated at 40, exceeds the force exerted by the pressure of the compressed gas in the control chamber 35 acting against the annular end surface 43 in addition to relatively small force exerted by the saring 44, then the discharge valve 2d is moved to the open position. As pointed out above, this takes place in the order of two milliseconds for the reason that, as soon as the discharge valve 24 moves away from the valve seat 26, the entire area of the left end of the discharge valve 24 is subjected to the pressure of the charge in the chamber 21 with the result that the discharge valve 24 moves quickly to the open position against the force exerted by the pressure of the cornpressed gas in the control chamber 35 and the relatively small force exerted by the spring 44. This action is accomplished by movement of the bottom wall 23 into engagement with the left side of the baffle 32 thus limiting the opening movement of the discharge valve 24. The volume of the chamber 3l) is reduced substantially to zero.

lt will be recalled that the pressure of the portion of the charge of the compressed gas in the intermediate chamber 34 is essentially the same as the pressure to which the chamber 2l was charged. Because of the presence of the baille 32 and the restricted orice means 38, this pressure in the intermediate chamber 34 is maintained at a relatively' high value although it is decreased slightly because of the movement of the discharge valve extension 39 to the right. The pressure of the compressed gas in the intermediate chamber 34 reacts against the annular surface 41 on the discharge valve extension 39 in a direction to hold the discharge valve 24 in the open position. The high pressure gas in the intermediate chamber 34 cannot be immediately discharged because of the restricted orifice means 38 which is the only vent for the intermediate chamber 34. Since the pressure in the intermediate chamber 34 is re.atively high as compared to the relatively low pressure in the control chamber 35, the force exerted by the pressure of the charge of compressed gas in the intermediate chamber 34 is sufficient to overcome the force exerted by the compressed gas in the control chambcr 35 and by the relatively weak spring 44 acting in a direction to close the discharge valve 24. This arrangement provides a substantial delay in the reclosing of the discharge valve 24 under the influence of the closing forces acting thereon and permits the charge in the chamber 2l. and whatever charge remains in the air supply tube 14 to be discharged through the discharge ports 2i) to such an extent that the charge in the chamber 21 is reduced substantially to zero.

In the event that the charge of compressed gas in the control chamber 35 has leaked out of it, the spring 44 acts to hold the discharge valve 24 in the closed position to permit the building up of pressure in the chambers 21 and 3U. As described, during the filling operation compressed air bleeds through the passageways 36 and 63 and lifts the ball check valve 60 to fill the control chamber 35 to the extent permitted by the relief valve member 66 under the control of the spring 69. Where the material breaking cartridge has not been used for a relatively long period, it is desirable that the initial iilling operation for the chambers 21 and 30 be carried out more slowly than is normally the case in order to make certain that the control chamber 35 is iilled to the required pressure for controlling the operation of the discharge valve 24 in the manner described.

Preferably the pressure of the compressed gas in the control chamber 35 is of the order of one-third to oneseventh of the pressure in the charge containing chamber 21 at which the discharge valve 24 is opened. The volume of the control chamber 35 is such that it is not reduced by more than 25 on movement of the valve extension 39 into it on opening of the discharge valve 24. With such a size for the control chamber 35, the increase in pressure therein resulting from movement of the valve extension 39 into it is not suicient to increase the pressure in the control chamber 35 to such an extent that opening movement of the discharge valve 24 is interfered with. For quick operation of the discharge valve 24 the area of the annular surface 41 at the left end of the discharge valve extension 39 is of the order of one-fourth to one-third the area of the annular end surface 43 at the right end of the valve extension 39.

FIG. 3 of the drawings shows a modification of the construction shown in FIGS. l and 2 and described hereinbefore. Where the various parts are identical, the same reference characters have been applied. Accordingly, the description will proceed with respect to the elements in FIG. 3 that are different from those shown in the preceding figures.

Restricted orifice means between the chamber 30` and the intermediate chamber 34 is provided in the form of an annular space 76 between the periphery of a transverse stationary baille 32' which corresponds to the ballie 32 previously described. Here the batiie 32 is carried by an imperforate stem 37 which extends to the left from a stationary piston 49 with respect to which the discharge valve extension 39 is movable and has sealed connection by the O ring seal 55. For assembly purposes the stem 37' is threaded at 77 into the stationary piston 49' and a lock nut 78 on the threaded portion of the stem 37' serves to hold it in fixed relation with respect to the stationary piston 49'. As stated, the restricted orifice means 76 is provided by an annular space between the periphery of the stationary baille 32' and the inner periphery of the discharge valve 24. For illustrative purposes it is pointed out that the radial dimension of the annular restricted passageway is of the order of .002" to .003. Such an arrangement permits the filling of the intermediate chamber 34 with a portion of the charge of high pressure gas that is supplied to the chambers 21 and 30 at a relatively slow rate as compared to the movement of the discharge valve 24 to the open position. Accordingly', the charge of highly compressed gas in the intermediate chamber 34 is substantially the same as the pressure in the chambers 21 and 30 before the discharge valve 24 opens and this pressure is maintained lto react against the annular surface 41 in a direction to hold the discharge valve 24 open for a time sufiicient to permit the chamber 21 to be completely discharged and for the charge in the air supply tube 14 also to be discharged all through the discharge ports In the construction shown in FIG. 3 the stationary piston 49' is formed integrally with a stem 79 which extends laterally from an end closure member 45' that corresponds to the end closure member 4S previously described. However, in this embodiment of the invention provision is made for permanently filling the control chamber 35 with a charge of compressed gas rather than providing for replenishing it each time that the chamber 21 is charged. For this purpose a longitudinal passageway 80 is provided in the end closure member 45 and extends into the stem 79 with a. lateral passageway S1 opening therefrom into the control chamber 35. A set screw valve 82 is threaded into a suitable centrally located threaded opening in the end closure member 45' and it has a conical end portion 83 for engaging a valve seat 84 at the right end of the passageway 80 for closing off the same after the control chamber 35 has been filled with the control charge of compressed gas. It will be noted that the set screw valve 82 has a transverse passageway 85 which communicates with an axial passageway 86 through which compressed gas can be supplied when the set screw valve 82 is backed off of sealing engagement with the valve seat 84. A kerf 87 permits operation of the set screw valve 82 to the open or closed position. A cap screw 88 is arranged to close the outer end of the central threaded aperture through the end closure member 45. It will be understood that the cap screw `88 is removed and that a suitable lling fixture is substituted therefor through which a tool can be inserted for engaging the kerf 87 in the set screw valve 82 for the purpose of opening it under pressure and then supplying the necessary charge of compressed gas to the control chamber 35, after which the set screw valve 82 is turned to the closed position. The filling fixture then is removed and the cap screw 88 is replaced.

Since the operation of the discharge valve 24 in response to application thereto of a predetermined pressure in `the chamber 21 is essentially as described hereinbefore in connection with the construction shown in FIGS. 1 and 2 of the drawings, the details of operation of the construction shown in FIG. 3 will not be repeated.

A further modification of the invention is shown in FIG. 4 of the drawings. Here it will be observed that provision is made for charging the intermediate chamber 34 through an axial passageway 36 extending through a transverse stationary baille 32" which corresponds to the baflie 32 shown in FIG. 2 and the baille 32' shown in FIG. 3. The baile 32" has a sealed sliding connection to the interior of the discharge valve 24 by the provision of the 0 ring seal 33. Restricted orifice means 38 in the form of a transverse passageway corresponding to the restricted orifice means 38 of FIG. 2 functions to place the intermediate chamber 34 in communication with the longitudinal passageway 36. The baille 32" is carried by a stem 37" which extends from a stationary piston 49" which corresponds to the piston 49 in FIG. 2 and the piston 49" in FIG. 3.

Priovision is made in the embodiment of the invention shown in FIG. 4 for varying the volume of the control chamber 35. For this purpose the relatively stationary piston 49" has a laterally extending stem 91 which is threaded at 92 to an end closure member 45" which corresponds to the end closure member 45 of FIG. 2 and 45' of FIG. 3. A kerf 93 in the outer end of the stem 91 provides for receipt of a suitable tool for rotating the stem 91 and thereby the relatively stationary piston 49" to move it relative to the end closure member 45" for either increasing or decreasing the volume of the control chamber 35 as the case may be. The stem 91 extends through a sleeve 94 which is an integral part of the end closure member 45" and an O ring seal 95 provides a sealed connection therebetween. Provision for filling the control chamber 35 is made by a longitudinal passageway 96 which extends axially of the stem 91 and communicates with a transverse passageway 97 into the control chamber 35. For closing the right end of the longitudinal passageway 9-6 there is provided the set screw valve 82 as described for FIG. 3. A cap screw 98 serves to close the opening through the end closure member 45" in the manner described for the cap screw 88 of FIG. 3. Since the operation of the discharge valve 24 for releasing the charge in the chamber 21 through the discharge port 70 is essentially the same as previously described for the operation of the discharge valve 24 in the construction shown in FIGS. 1 and 2, the description will not be repeated.

While the constructions shown in FIGS. 3 and Li of the drawings contemplate that `the control chamber 3S will permanently fold `a charge of compressed gas, experience indicates that it is not possible to confine this charge permanently, Where there are moving parts and. relatively high pressure there is some deterioration in the seals and consequent lealtage of the gas from the control chamber 35. lvith a view to overcoming a slow leak of the compressed gas from the chamber 35 in the construction shown in FlGS. 3 and 4 this chamber can be supplied with a sealing liquid which occupies a relatively small portion, for example of the volume of the control chamber 35. Lubricating oil can be employed for this purpose and it provides for both sealing and lubricating the pants. Alternatively, the control chamber can be charged with a liquid having a vapor pressure characteristic that provides the necessary pressure for the operating temperature.

We claim as our invention:

l. In a device for breaking down material, such coal, slag and the like in which a charge of highly compressed gas is quickly released from a charge containing chamber through lateral disch-.urge ports as a result ot' movement of an annular discharge valve away from scaling engagement between one end thereof and an annular seat located cn thc chamber adjacent said discharge ports and held thcreagainst principally by gas at predetermined pressure in a control chamber endwise of said charge containing chamber and on the side of said ports opposite said annular seat until the force resulting from pressure in said charge containing chamber and acting on said one end of said discharge valve in an opening direction exceeds the force resulting from gas pressure in said control charnbcr acting on the other cud of said discharge valve in a closing direction whereupon said discharge valve is moved to open position to permit said charge to be released through said ports accompanied by a reduction in said force acting to open said discharge valve and the tendency thereof to rcclose and trap a portion of the charge in said chamber containing the same and resulting from said force exerted by the gas in said control chamber acting to close said discharge valve, the improvement which provides for delaying the closing movement of said discharge valve for a time sufficient to effect a substantially complete release of said charge from said chamber eon taining the same comprising:

(a) means providing an intermediate chamber between said charge containing chamber and said control chamber whose volume increases as said discharge valve moves to open position, said intermediate chamber being defined by:

(l) a stationary baffle extending transversely of and telescoped within said annular discharge valve,

(2) a stationary piston spaced from said baille and telescoped within said annular discharge valve and located between said intermediate chamber and said control chamber,

(3) a stern interconnecting said baille piston,

and (fl) said annular discharge valve,

(b) and restricted orifice means placing said intermediate chamber in communication with said charge containing chamber whereby a portion of said charge tlows into said intermediate chanibcr and applies a force to said discharge valve in the valve opening direction which force is maintained substantially undiminishcd due to said restricted oriicc means while .tl in suizl charge containing chamber is released through said ports and which force exceeds said torce exerted on said discharge valve resulting from gas pressure in said control chamber in a closing direction until the charge in said intermediate chamber is released through said restricted orifice means whereupon said discharge valve is recilosed.

2. The invention, as set forth in claim l, wherein the discharge valve has an annular area facing the stationary battle against which arca the pressure of the charge in the intermediate chamber reacts in a direction to open said valve and hold the same open.

3. 'lhe invention, as Set forth in claim l, wherein the restricted orifice means is a passageway extending through the baille.

4. The invention, as set forth in claim l, wherein a passageway interconnects the charge containing chamber and. the control chamber whereby the gas therein acting to bias the discharge valve toward Closed position is a part of the charge of gas supplied to said charge containing` chamber.

5. The invention, as set forth in claim 4, wherein a checl'` valve in the passageway prevents discharge of the gas from the control chamber.

(i. The invention, as set forth in claim 4, wherein the control chamber is connected to the atmosphere through a relief valve arranged and adapted to limit the gas pressure in said control chamber to a predetermined pressure.

7. The invention, as set forth in claim l, wherein the restricted orifice means is a passageway in the form of an annular space between the periphery of the baille and thc inside of the annular discharge valve.

8. The invention, as set forth in claim l, wherein the control chamber is permanently sealed and it is filled with a gas at predetermined pressure.

9. The invention, as set forth in claim l, wherein the stationary piston is characterized by being adjustable to effect Corresp-ending variation in the volume 'of the control chamber.

lll. The invention, as set forth in claim l, wherein the control chamber is partially filled with a sealing liquid.

l l. The invention, as set forth in claim lt), wherein the sealing liquid is a lubricating oil.

References Cited in the filc of this patent UNITED STATES PATENTS 2,532,578 Spencer Dec. 5, D 

1. IN A DEVICE FOR BREAKING DOWN MATERIAL, SUCH AS COAL SLAG AND THE LIKE IN WHICH A CHARGE OF HIGHLY COMPRESSED GAS IS QUICKLY RELEASED FROM A CHARGE CONTAINING CHAMBER THROUGH LATERAL DISCHARGE PORTS AS A RESULT OF MOVEMENT OF AN ANNULAR DISCHARGE VALVE AWAY FROM SEALING ENGAGEMENT BETWEEN ONE END THEREOF AND AN ANNULAR SEAT LOCATED ON THE CHAMBER ADJACENT SAID DISCHARGE PORTS AND HELD THEREAGAINST PRINCIPALLY BY GAS PREDETERMINED PRESSURE IN A CONTROL CHAMBER ENDWISE OF SAID CHARGE CONTAINING CHAMBER AND ON THE SIDE OF SAID PORTS OPPOSITE SAID ANNULAR SEAT UNTIL THE FORCE RESULTING FROM PRESSURE IN SAID CHARGE CONTAINING CHAMBER AND ACTING ON SAID ONE END OF SAID DISCHARGE VALVE IN AN OPENING DIRECTION EXCEEDS THE FORCE RESULTING FROM GAS PRESSURE IN SAID CONTROL CHAMBER ACTING ON THE OTHER END OF DISCHARGE VALVE IN A CLOSING DIRECTION WHEREUPON SAID DISCHARGE VALVE IS MOVED TO OPEN POSITION TO PERMIT SAID CHARGE TO BE RELEASED THROUGH SAID PORTS ACCOMPANIED BY A REDUCTION IN SAID FORCE ACTING TO OPEN SAID DISCHARGE VALVE AND THE TENDENCY THEREOF TO RECLOSE AND TRAP A PORTION OF THE CHARGE IN SAID CHAMBER CONTAINING THE SAME AND RESULTING FROM SAID FORCE EXERTED BY THE GAS IN SAID CONTROL CHAMBER ACTING TO CLOSE SAID DISCHARGE VALVE, THE IMPROVEMENT WHICH PROVIDES FOR DELAYING THE CLOSING MOVEMENT OF SAID DISCHARGE VALVE FOR A TIME SUFFICIENT TO EFFECT A SUBSTANTIALLY COMPLETE RELEASE OF SAID CHARGE FROM SAID CHAMBER CONTAINING THE SAME COMPRISING: (A) MEANS PROVIDING AN INTERMEDIATE CHAMBER BETWEEN SAID CHARGE CONTAINING CHAMBER AND SAID CONTROL CHAMBER WHOSE VOLUME INCREASES AS SAID DISCHARGE VALVE MOVES TO OPEN POSITION, SAID INTERMEDIATE CHAMBER BEING DEFINED BY: (1) A STATIONARY BAFFLE EXTENDING TRANSVERSELY OF AND TELESCOPED WITHIN SAID ANNULAR DISCHARGE VALVE, (2) A STATIONARY PISTON SPACED FROM SAID BAFFLE AND TELESCOPED WITHIN SAID ANNULAR DISCHARGE VALVE AND LOCATED BETWEEN SAID INTERMEDIATE CHAMBER AND SAID CONTROL CHAMBER, (3) A STEM INTERCONNECTING SAID BAFFLE AND PISTON, AND (4) SAID ANNULAR DISCHARGE VALVE, (B) AND RESTRICTED ORIFICE MEANS PLACING SAID INTERMEDIATE CHAMBER IN COMMUNICATION WITH SAID CHARGE CONTAINING CHAMBER WHEREBY A PORTION OF SAID CHARGE FLOWS INTO SAID INTERMEDIATE CHAMBER AND APPLIES A FORCE TO SAID DISCHARGE VALVE IN THE VALVE OPENING DIRECTION WHICH FORCE IS MAINTAINED SUBSTANTIALLY UNDIMINISHED DUE TO SAID RESTRICTED ORIFICE MEANS WHILE SAID CHARGE IN SAID CHARGE CONTAINING CHAMBER IS RELEASED THROUGH SAID PORTS AND WHICH FORCE EXCEEDS SAID FORCE EXERTED ON SAID DISCHARGE VALVE RESULTING FROM GAS PRESSURE IN SAID CONTROL CHAMBER IN A CLOSING DIRECTION UNTIL THE CHARGE IN SAID INTERMEDIATE CHAMBER IS RELEASED THROUGH SAID RESTRICTED ORIFICE MEANS WHEREUPON SAID DISCHARGE VALVE IS RECLOSED. 